Renewable Energy Curtailment Storage in Molten Salt and Solid Particle Solar Thermal Power Plants: A Comparative Analysis in Spain
Source abstract
Abstract
Spain’s energy transition poses the dual challenge of managing renewable curtailment and enhancing the competitiveness of concentrated solar power (CSP) technologies. This study evaluates the suitability of replacing molten salts with solid particles for energy storage and, additionally, explores the storage of surplus electricity from grid in Carnot batteries. Four scenarios were analyzed using a Gemasolar-type plant model: each storage medium was studied with and without the integration of curtailed electricity. The solar field was modeled with SAM (System Advisor Model), while curtailment data from Red Eléctrica de España (2016–2021) quantified the available surplus. Results show that solid particles lead to 7.4% higher annual electricity production compared to molten salts, mainly due to improved power cycle efficiency. The integration of curtailment increased output further, with the solid particle Carnot battery scenario achieving the highest performance (up to 19.0% sun-to-electricity efficiency and 69.7% capacity factor). However, round-trip efficiency for curtailment storage was limited (~25–27%), and although solid particles showed lower LCOE (levelized cost of energy) than salts (192 vs. 211 USD/MWh), the Carnot battery increased costs. These findings suggest that while solid particles offer clear advantages, the economic viability of Carnot batteries remains constrained by current cost and operational limitations.
Source: crossref · Quality: baseline
Research context
OpenAlex topics: Solar Thermal and Photovoltaic Systems · Phase Change Materials Research · Building Energy and Comfort Optimization
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
Affiliations
Department of Chemical and Energy Technology, School of Experimental Sciences and Technology (ESCET), Rey Juan Carlos University, 28933 Madrid, Spain
References (80)
Show source-provided references
1. Global Warming: Review on Driving Forces and Mitigation10.1002/ep.13041 ↗
2. Thermo-Economic Design of an Electric Heater to Store Renewable Curtailment in Solar Power Tower Plants10.1016/j.enconman.2023.117710 ↗
3. (2025, May 25). MITECO Plan Nacional Integrado de Energía y Clima (PNIEC) 2021–2030. Available online: https://www.miteco.gob.es/es/prensa/pniec.html.
4. (2025, May 25). Red Eléctrica REData—Potencia Instalada. Available online: https://www.ree.es/es/datos/generacion/potencia-instalada.
5. Kost, C., Mayer, J.N., Thomsen, J., Hartmann, N., Senkpiel, C., Philipps, S., Nold, S., Lude, S., Saad, N., and Schlegl, T. (2013). Levelized Cost of Electricity—Renewable Energy Technologies, Fraunhofer ISE.
6. Thermal Energy Storage Technologies for Concentrated Solar Power—A Review from a Materials Perspective10.1016/j.renene.2019.10.127 ↗
7. (2025, May 25). IRENA Concentrated Solar Power: Technology Brief. Available online: https://www.irena.org/publications/2013/Jan/Concentrated-Solar-Power.
8. The Electricity Production Capacity of Photovoltaic Power Plants and the Selection of Solar Energy Sites in Andalusia (Spain)10.1016/j.renene.2007.05.041 ↗
9. Frolova, M., Prados, M.-J., and Nadaï, A. (2015). Renewable Energies and European Landscapes: Lessons from Southern European Cases, Springer.10.1007/978-94-017-9843-3 ↗
10. Analyzing Territory for the Sustainable Development of Solar Photovoltaic Power Using GIS Databases10.1007/s10661-019-7871-8 ↗
11. (2025, May 25). IRENA Renewable Power Generation Costs in 2022. Available online: https://www.irena.org/Publications/2023/Aug/Renewable-Power-Generation-Costs-in-2022.
12. Review of High-Temperature Central Receiver Designs for Concentrating Solar Power10.1016/j.rser.2013.08.099 ↗
13. A High-Efficiency Solar Thermal Power Plant Using a Dense Particle Suspension as the Heat Transfer Fluid10.1016/j.egypro.2015.03.191 ↗
14. Renewable Energy Curtailment: A Case Study on Today’s and Tomorrow’s Congestion Management10.1016/j.enpol.2017.10.037 ↗
15. The Curtailment Paradox in the Transition to High Solar Power Systems10.1016/j.joule.2021.03.021 ↗
16. Hourly-Resolution Analysis of Electricity Decarbonization in Spain (2017–2030)10.1016/j.apenergy.2018.10.055 ↗
17. Facing the High Share of Variable Renewable Energy in the Power System: Flexibility and Stability Requirements10.1016/j.apenergy.2022.118561 ↗
18. Battery Energy Storage Systems in Energy and Reserve Markets10.1109/TPWRS.2019.2936131 ↗
19. Modelling and Optimal Energy Management for Battery Energy Storage Systems in Renewable Energy Systems: A Review10.1016/j.rser.2022.112671 ↗
20. A Comprehensive Review on Solid Particle Receivers of Concentrated Solar Power10.1016/j.rser.2019.109463 ↗
21. Opportunities and Challenges in Using Particle Circulation Loops for Concentrated Solar Power Applications10.1016/j.pecs.2022.101056 ↗
22. Martínez, S.M., Lázaro, E.G., Escribano, A.H., Carretón, M.C., and Molina-Garcia, A. (2015, January 26–30). Wind Power Curtailment Analysis under Generation Flexibility Requirements: The Spanish Case Study. Proceedings of the 2015 IEEE Power & Energy Society General Meeting, Denver, CO, USA.10.1109/PESGM.2015.7286110 ↗
23. C-E (Curtailment—Energy Share) Map: An Objective and Quantitative Measure to Evaluate Wind and Solar Curtailment10.1016/j.rser.2022.112212 ↗
24. (2025, May 02). Red Eléctrica de España Descargas|ESIOS. Available online: https://www.esios.ree.es/es/descargas.
25. Boletín Oficial del Estado (2022). Resolución de 17 de Marzo de 2022, de La Comisión Nacional de Los Mercados y La Competencia, Por La Que Se Aprueban Los Procedimientos de Operación Adaptados a La Programación Cuarto-Horaria de La Operación Del Sistema Eléctrico Peninsular Español, Boletín Oficial del Estado.
26. (2025, May 25). NREL Gemasolar Thermosolar Plant/Solar TRES|Concentrating Solar Power Projects|NREL, Available online: https://solarpaces.nrel.gov/project/gemasolar-thermosolar-plant-solar-tres.
27. Burgaleta, J.I., Arias, S., and Ramirez, D. (2011, January 20–23). Gemasolar, the first tower thermosolar commercial plant with molten salt storage. Proceedings of the SolarPACES, Granada, Spain.
28. Simulation of GEMASOLAR-Based Solar Tower Plants for the Chinese Energy Market: Influence of Plant Downsizing and Location Change10.1016/j.renene.2012.12.022 ↗
29. Annual Comparative Performance and Cost Analysis of High Temperature, Sensible Thermal Energy Storage Systems Integrated with a Concentrated Solar Power Plant10.1016/j.solener.2017.05.044 ↗
30. Thermodynamic Performance Assessment of a New Solar Tower-Geothermal Combined Power Plant Compared to the Conventional Solar Tower Power Plant10.1016/j.energy.2021.121109 ↗
31. Review of Commercial Thermal Energy Storage in Concentrated Solar Power Plants: Steam vs. Molten Salts10.1016/j.rser.2017.05.084 ↗
32. Review on Concentrating Solar Power Plants and New Developments in High Temperature Thermal Energy Storage Technologies10.1016/j.rser.2015.09.026 ↗
33. Molten Salts Database for Energy Applications10.1016/j.cep.2013.07.008 ↗
34. Lantelme, F., and Groult, H. (2013). Molten Salts Chemistry: From Lab to Applications, Elsevier. [1st ed.].
35. (2025, May 26). NREL CSP Validation 2013, Available online: https://sam.nrel.gov/concentrating-solar-power/csp-validation.html.
36. Bradshaw, R.W., Dawson, D.B., De La Rosa, W., Gilbert, R., Goods, S.H., Hale, M.J., Jacobs, P., Jones, S.A., Kolb, G.J., and Pacheco, J.E. (2002). Final Test and Evaluation Results from the Solar Two Project, Sandia National Lab. (SNL-CA).10.2172/793226 ↗
37. Heat Transfer and Thermal Performance of Two-Stage Molten Salt Steam Generation System10.1016/j.apenergy.2017.04.010 ↗
38. Heat Transfer Performance of U-Tube Molten Salt Steam Generator10.1016/j.ijheatmasstransfer.2020.120200 ↗
39. Reilly, H.E., and Kolb, G.J. (2001). An Evaluation of Molten-Salt Power Towers Including Results of the Solar Two Project, Sandia National Lab. (SNL-CA).10.2172/791898 ↗
40. Two-Tank Molten Salt Storage for Parabolic Trough Solar Power Plants10.1016/S0360-5442(03)00193-2 ↗
41. Review on Gas-Solid Fluidized Bed Particle Solar Receivers Applied in Concentrated Solar Applications: Materials, Configurations and Methodologies10.1016/j.rser.2021.111479 ↗
42. Experimental Results for a MW-Scale Fluidized Particle-in-Tube Solar Receiver in Its First Test Campaign10.1016/j.solener.2023.111907 ↗
43. Annual Performance of Subcritical Rankine Cycle Coupled to an Innovative Particle Receiver Solar Power Plant10.1016/j.renene.2018.06.109 ↗
44. Heat Exchanger Modelling in Central Receiver Solar Power Plant Using Dense Particle Suspension10.1063/1.4984385 ↗
45. Design Analysis of a Particle-Based Thermal Energy Storage System for Concentrating Solar Power or Grid Energy Storage10.1016/j.est.2020.101382 ↗
46. Design Considerations for Commercial Scale Particle-Based Thermal Energy Storage Systems10.1063/5.0086995 ↗
47. Thermo-Mechanical Concepts for Bulk Energy Storage10.1016/j.rser.2016.10.065 ↗
48. Novotny, V., Basta, V., Smola, P., and Spale, J. (2022). Review of Carnot Battery Technology Commercial Development. Energies, 15.10.3390/en15020647 ↗
49. Carnot Battery Application in a Parabolic Trough Concentrating Solar Power Plant: System Modelling, Validation and Analyses on the Interplay between Stored Energies10.1016/j.est.2022.106545 ↗
50. Carnot Battery Technology: A State-of-the-Art Review10.1016/j.est.2020.101756 ↗
51. A High-Temperature Heat Pump for Compressed Heat Energy Storage Applications: Design, Modeling, and Performance10.1016/j.egyr.2022.08.201 ↗
52. Predictive Storage Strategy for Optimal Design of Hybrid CSP-PV Plants with Immersion Heater10.1016/j.solener.2020.11.005 ↗
53. Iñigo-Labairu, J., Dersch, J., and Schomaker, L. (2022). Integration of CSP and PV Power Plants: Investigations about Synergies by Close Coupling. Energies, 15.10.3390/en15197103 ↗
54. Simultaneous Design and Operational Optimization of Hybrid CSP-PV Plants10.1016/j.apenergy.2022.120369 ↗
55. Nuclear Air-Brayton Power Cycles with Thermodynamic Topping Cycles, Assured Peaking Capacity, and Heat Storage for Variable Electricity and Heat10.1080/00295450.2020.1785793 ↗
56. sandTES—An Active Thermal Energy Storage System Based on the Fluidization of Powders10.1016/j.egypro.2014.03.106 ↗
57. Flexible Electricity Dispatch for CSP Plant Using Un-Fired Closed Air Brayton Cycle with Particles Based Thermal Energy Storage System10.1016/j.energy.2019.02.135 ↗
58. Thermodynamic Properties of Air and Mixtures of Nitrogen, Argon, and Oxygen From 60 to 2000 K at Pressures to 2000 MPa10.1063/1.1285884 ↗
59. Heat Transfer and Pressure Loss of a Very Shallow Fluidized-Bed Heat Exchanger Part 2. Experiment with Multirow Tube Banks10.1016/0894-1777(88)90013-1 ↗
60. Towler, G.P., and Sinnott, R.K. (2022). Chemical Engineering Design: Principles, Practice and Economics of Plant and Process Design, Butterworth-Heinemann. [3rd ed.].
61. Perry, J.H., Green, D.W., and Southard, M.Z. (2019). Perry’s Chemical Engineers’ Handbook, McGraw-Hill Education. [9th ed.].
62. (2025, May 26). NREL System Advisor Model (SAM) Case Study: Gemasolar 2013, Available online: https://sam.nrel.gov/images/web_page_files/sam_case_csp_salt_tower_gemasolar_2013-1-15.pdf.
63. Off-Design Simulation and Performance of Molten Salt Cavity Receivers in Solar Tower Plants under Realistic Operational Modes and Control Strategies10.1016/j.apenergy.2016.07.032 ↗
64. Lovegrove, K., and Stein, W. (2020). Concentrating Solar Power Technology: Principles, Developments and Applications, Woodhead.10.1016/B978-0-12-819970-1.00012-8 ↗
65. Temperature Distribution and Heat Losses in Molten Salts Tanks for CSP Plants10.1016/j.solener.2016.06.030 ↗
66. Impact of DNI Forecasting on CSP Tower Plant Power Production10.1016/j.renene.2019.01.095 ↗
67. (2025, May 02). Crescent Dunes Solar Energy Project|Concentrating Solar Power Projects|NREL, Available online: https://solarpaces.nrel.gov/project/crescent-dunes-solar-energy-project.
68. (2025, May 02). Atacama I/Cerro Dominador 110MW CSP + 100MW PV|Concentrating Solar Power Projects|NREL, Available online: https://solarpaces.nrel.gov/project/atacama-i-cerro-dominador-110mw-csp-100mw-pv.
69. Avila-Marin, A., Fernández-Reche, J., Monterreal, R., Ballestrin, J., Gallego, J.F., Casanova, M., Escorza, S., Mutuberria, A., Kämpgen, A., and Macke, A. (2013, January 8–13). Testing and Validation of Innovative On-Site Solar Field Measurement Techniques to Increase Power Tower Plant Performance: The LEIA Project. Proceedings of the SolarPACES 2023, 29th International Conference on Concentrating Solar Power, Thermal, and Chemical Energy Systems, Sydney, Australia.10.52825/solarpaces.v2i.777 ↗
70. A Review of Large-Scale Electrical Energy Storage10.1002/er.3294 ↗
71. (2025, May 25). Redeia Non Renewable Detail CO2 Emissions. Available online: https://www.ree.es/en/datos/generation/non-renewable-detail-CO2-emissions?end_date=2021-12-31T23:59&start_date=2016-01-01T00:00&systemElectric=nacional&time_trunc=year_2.
72. Carnot Battery Development: A Review on System Performance, Applications and Commercial State-of-the-Art10.1016/j.est.2022.105782 ↗
73. (2025, May 25). Eurostat HICP—Annual Data (Average Index and Rate of Change). Available online: https://ec.europa.eu/eurostat/databrowser/product/page/PRC_HICP_AIND.
74. Power-to-Heat for the Industrial Sector: Techno-Economic Assessment of a Molten Salt-Based Solution10.1016/j.enconman.2022.116362 ↗
75. Demonstration of a Multi-Channel Fluidized Bed Particle–Supercritical Carbon Dioxide Heat Exchanger for Concentrating Solar Applications10.1016/j.applthermaleng.2024.123242 ↗
76. Techno-Economic Analysis of H2 Production Processes Using Fluidized Bed Heat Exchangers with Steam Reforming—Part 1: Oxygen Carrier Aided Combustion10.1016/j.ijhydene.2019.10.202 ↗
77. A Thermo-Economic Analysis and Comparison of Pumped-Thermal and Liquid-Air Electricity Storage Systems10.1016/j.apenergy.2018.04.128 ↗
78. (2025, May 25). Eurostat Electricity Prices for Non-Household Consumers—Bi-Annual Data (from 2007 Onwards). Available online: https://ec.europa.eu/eurostat/databrowser/product/page/NRG_PC_205.
79. Technical and Economic Evaluation, Comparison and Optimization of a Carnot Battery with Two Different Layouts10.1016/j.est.2022.105583 ↗
80. Optimal Integration of Solar Collectors to Carnot Battery System with Regenerators10.1016/j.enconman.2022.116625 ↗